NM_001267550.2:c.71476G>C

Variant names:

• chr2-178574656-C-G
• rs377751708
• NM_001267550.2:c.71476G>C

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_001267550.2(TTN):​c.71476G>C​(p.Val23826Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000287 in 1,460,890 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. V23826V) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000029 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 6.13
• Publications: 2 publications found

Genes affected

TTN (HGNC:12403): (titin) This gene encodes a large abundant protein of striated muscle. The product of this gene is divided into two regions, a N-terminal I-band and a C-terminal A-band. The I-band, which is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine. The A-band, which is thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity. An N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere, respectively, so that a single titin molecule spans half the length of a sarcomere. Titin also contains binding sites for muscle associated proteins so it serves as an adhesion template for the assembly of contractile machinery in muscle cells. It has also been identified as a structural protein for chromosomes. Alternative splicing of this gene results in multiple transcript variants. Considerable variability exists in the I-band, the M-line and the Z-disc regions of titin. Variability in the I-band region contributes to the differences in elasticity of different titin isoforms and, therefore, to the differences in elasticity of different muscle types. Mutations in this gene are associated with familial hypertrophic cardiomyopathy 9, and autoantibodies to titin are produced in patients with the autoimmune disease scleroderma. [provided by RefSeq, Feb 2012]

TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.17592499).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001267550.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.71476G>C	p.Val23826Leu	missense	Exon 326 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.66553G>C	p.Val22185Leu	missense	Exon 276 of 313	NP_001243779.1
	TTN	NM_133378.4		c.63772G>C	p.Val21258Leu	missense	Exon 275 of 312	NP_596869.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.71476G>C	p.Val23826Leu	missense	Exon 326 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.71320G>C	p.Val23774Leu	missense	Exon 324 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.71200G>C	p.Val23734Leu	missense	Exon 324 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000161 AC: 4 AN: 247978 AF XY: 0.0000149

Gnomad AFR exome AF: 0.0000646

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000267

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000287 AC: 42 AN: 1460890 Hom.: 0 Cov.: 38 AF XY: 0.0000303 AC XY: 22 AN XY: 726690

African (AFR) AF: 0.00 AC: 0 AN: 33456

American (AMR) AF: 0.00 AC: 0 AN: 44686

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26080

East Asian (EAS) AF: 0.00 AC: 0 AN: 39608

South Asian (SAS) AF: 0.00 AC: 0 AN: 86142

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53376

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5758

European-Non Finnish (NFE) AF: 0.0000378 AC: 42 AN: 1111448

Other (OTH) AF: 0.00 AC: 0 AN: 60336

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000282 Hom.: 0

Bravo AF: 0.0000113

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.00 AC: 0

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000121 AC: 1

ExAC AF: 0.0000248 AC: 3

EpiCase AF: 0.0000546

EpiControl AF: 0.0000594

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Uncertain:1

Jun 05, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Cardiomyopathy Uncertain:1

Jul 06, 2021

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.22
BayesDel_addAF	Benign	-0.20	T
BayesDel_noAF	Benign	-0.34
CADD	Benign	21
DANN	Benign	0.92
Eigen	Uncertain	0.49
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.88	D
M_CAP	Benign	0.016	T
MetaRNN	Benign	0.18	T
MetaSVM	Benign	-0.72	T
MutationAssessor	Benign	1.4	L
PhyloP100		6.1
PrimateAI	Uncertain	0.74	T
PROVEAN	Benign	-2.1	N
REVEL	Benign	0.14
Sift	Benign	0.15	T
Polyphen		0.74	P
Vest4		0.33
MVP		0.31
MPC		0.17
ClinPred		0.14	T
GERP RS		5.5
Mutation Taster		=81/19	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs377751708; hg19: chr2-179439383;